Alliance Semiconductor ASM161, ASM162 Service Manual

查询ASM162供应商

October 2003

rev 1.0

General Description

The ASM161 and ASM162 are cost effective, low power

supervisory circuits that monitor power supplies in

microprocessor, microcontroller and digital systems. If the

power supply drops below the reset threshold level, a reset is

asserted and remains asserted for atleast 800ms after V

risen above the reset threshold. An improved manual reset

architecture gives the system designer additional flexibility.

The debounced manual reset input is negative edge triggered.

The reset pulse period generated by a MR

minimum of 800 ms and a maximum of 2 sec duration. In

addition, The MR

minimum after the reset pulse ends. During the MR

period, the microcontroller is guaranteed a time period free of

additional manual reset signals. During this period DRAM

contents can be refreshed or other critical system tasks

undertaken. Low power consumption makes the ASM161/162

ideal for use in portable and battery operated equipments. With

3V supplies power consumption is 8µW typically and 30µW

maximum. The ASM161 has an open-drain, active-LOW

RESET

output and requires an external pull-up resistor. The

ASM162 has an active HIGH RESET output.

input signal is blocked for an additional 49µS

µP Supervisory Circuit

has

CC

transition is a

disable

ASM161 / ASM162

Key Features

• Edge triggered manual reset input

• single pulse output

• 49µS minimum MR

• CMOS/TTL logic or switch interface

• Debounced input

• Low supply current extends battery life

• 6µA / 15µA typ/max at 5.5V

• 4.5µA / 10µA typ/max at 3.6V

• Long reset period

• 0.8 sec minimum, 2 sec maximum

• Two reset polarity options

• ASM161: Active LOW, open-drain

• ASM162: Active HIGH

• Pinout matches the AS811/812

• Small 4-Pin SOT-143 package

• Two temperature ranges: 0

Applications

•PDAs

• Appliances

• Computers and embedded controllers

• Wireless communication systems

• Battery operated and intelligent instruments

• Automotive systems

• Safety systems

Typical Operating Circuit

disable period after reset

0

0

to 70

c and -400c to +850c

The ASM161/162 are offered in compact 4-pin SOT-143

packages. No external components are required to trim

threshold voltage for monitoring different supply voltages. With

six different factory set, reset, threshold ranges from 2.63V to

4.63V, the ASM161/162 are suitable for monitoring 5V, 3.6V

and 3.0V supplies. The ASM161/162 are available in

temperature ranges 0

Reset Threshold

Part Suffix Voltage (V)

L4.63

M4.38

J4.00

T3.08

S2.93

R2.63

0

to 700c and -400c to +850c.

Alliance Semiconductor

2575 Augustine Drive . Santa Clara, CA 95054 . Tel: [phone] . Fax: [phone] . www.alsc.com

Notice: The information in this document is subject to change without notice

V

CC

V

CC

ASM161

(ASM162)

MR

GND

RESET

(RESET)

20k for
ASM161
only

RESET

(RESET)

V

µP

GND

CC

October 2003

rev 1.0

Block Diagram

4

V

CC

MR

Pin Configuration

Voltage
Divider

3

MR

Debounce

* Non-retriggerable, edge

triggered manual reset

ASM161 / ASM162

V

-

+

Bandgap
Reference

1

GND

SOT-143

ASM161/162

Circuit

Reset

* Edge Trigger

2

(ASM161)

RESET
RESET (ASM162)

ASM161

~

~

Reset

Circuit

~

~

SOT-143

CC

4

R

PU

2

GND

1

ASM161

RESET

2

RESET is open drain

Pin Description

Pin #

Pin Name Description

ASM161 ASM162

1 1 GND Ground.

2 - RESET

- 2 RESET

33MR

V

4

CC

GND

1

V

4

CC

ASM162

MR

3

Active-LOW, open-drain reset output. RESET remains LOW while VCC is below the

reset threshold and for 800ms minimum after V

An external pull-up resistor is needed.

Active HIGH reset output. RESET remains HIGH while V

threshold and for 800ms after V

Manual reset input. A negative going edge transition on MR asserts reset. Reset
remains asserted for one reset time-out period (800 ms min). This active-LOW
input has an internal pull-up resistor. It can be driven from a TTL or CMOS logic line
or shorted to ground with a switch. Leave open if unused.

RESET

2

rises above the reset threshold.

CC

CC

rises above the reset threshold.

CC

MR

3

is below the reset

44

V

Notice: The information in this document is subject to change without notice

CC

Power supply input voltage.

2 of 9

µP Supervisory Circuit

October 2003

rev 1.0

ASM161 / ASM162

Detailed Descriptions

The reset function ensures the microprocessor is properly

reset and powers up into a known condition after a power

failure.

Reset Timing

A reset is generated whenever the supply voltage is below

the threshold level (V

800ms after VCC has risen above the reset threshold and is

guaranteed to be no more than 2 seconds. The rest signal

remains active as long as the monitored supply voltage is

below the internal threshold voltage.

The ASM161 has an open-drain, active LOW RESET

(which is guaranteed to be in the correct state for V

to 1.1 V). The ASM161 uses an external pull-up resistor.

Output leakage current is under 1µA. A high resistance value

can be used to minimize current drain.

The ASM162 generates an active-HIGH RESET output.

Part Number Reset Polarity

ASM161 LOW (use external pull-up resistor)

ASM162 HIGH

Manual Reset

The ASM161/162 have a unique manual reset circuit. A

negative going edge transition on MR

manual reset generates a single reset pulse of fixed length.

The output-reset pulse remains asserted for the Reset Active

Time-Out Period t

completed, the MR

but not more than 122µS. This period is specified as t

During the MR

guaranteed a time period free of new manual reset signals.

This period can be used to refresh critical DRAM contents or

other system tasks.

< VTH). The reset duration is at least

CC

output

down

CC

initiates the reset. A

and then clears. Once the reset pulse is

RP

input remains disabled for at least 49µS

disabled period, the microcontroller is

MRD

.

The MR

t

MRD

pulse.

The manual reset input has an internal 20kΩ pull-up resistor.

MR

pin must be taken HIGH and LOW again after the

period has been completed to initiate another reset

can be left open if not used.

t

MD

MR

RESET

*........

Triggering

Reset

Time-Out

MR input is blocked

Pulse

t

MRD

*Second and following edges ignored

Figure 1: Manual Reset Timing

Application Information

Glitch Resistance

The ASM161/162 are relatively immune to short duration

negative-going V

goes 100mV below the reset threshold and lasts 20s or less

will not typically cause a reset pulse.

Figure 2:

Valid Reset with V

To ensure that logic inputs connected to the ASM162 RESET

pin are in a known state when V

pull-down resistor at RESET is needed. The value is not

critical.

This scheme does not work with the open-drain outputs of

ASM161.

transients/glitches. A VCC transient that

CC

V

Power Supply

ASM162

MR

GND

CC

RESET

100K

Ω

RESET valid with VCC under 1.1V

CC under 1.1V

is under 1.1V, a 100kΩ

CC

Ready

for

next

MR

µP Supervisory Circuit

Notice: The information in this document is subject to change without notice

3 of 9